1. Field of the Invention
The present invention pertains to the measurement of flowing fluids. More particularly, it concerns the measurement of fluid flow velocity and the volumetric flow rate of liquids and liquid/solid mixtures.
2. Description of Related Art
It has long been desirable to determine the amount of fluid flowing from an underground system or from culverts, ditches, conduits, pipes and the like so that a determination can be made with respect to overflow, breaks in the system or other problems that may result in unwanted flow restriction, leaks or stoppage. Attempts to measure flowing liquids have oftentimes incorporated movable cones as shown in U.S. Pat. No. 1,164,441 or drums having spaced-apart blades such as that shown in U.S. Pat. No. 1,025,227. Such systems translate the rotational spinning of the cones or drum blades into flow velocity data through worm gears, clock-like mechanical linkages and cables.
Problems with the above systems are their inaccuracy. Also, they require frequent maintenance and replacement of broken or worn-out parts. Additionally, many of the systems require a separate floating mechanism upon which is mounted a paddle-wheel device. Such devices are shown in U.S. Pat. No. 4,195,521 and U.S. Pat. No. 530,337. Using an additional float device creates multiple opportunities for inaccurate velocity readings because the float disturbs the natural flow of water toward the paddle wheel. Moreover, the float devices attract debris, accumulations of dirt and aquatic plants which denigrate the accuracy of the flow measurements and fluid levels being determined.
The present invention overcomes the above disadvantages by providing a flow indicator assembly that utilizes sensors and electronic instruments for measuring flowing fluids through a defined channel. The system does not require an additional floating mechanism nor mechanical linkages which are prone to malfunction. As used herein, the term fluid encompasses liquids, liquid colloidal suspensions slurries and entrained solid particulates in a moving liquid. A defined channel may be an open ditch, flume, stream bed, trough or on enclosed pipe, conduit or culvert.
In particular, the present invention provides a flow indicator assembly comprising a support structure positioned adjacent a stream of moving fluid, an elongated arm pivotally attached to the support structure arm and a barrel that is rotatably mounted to the lower-end portion of the arm. The arm can thereby swing the barrel in and out of a stream of fluid.
The barrel includes a rotation sensor which provides an electronic signal to a signal processor which computes the velocity of the fluid moving past the barrel. Also, the arm may include an angular position sensor which can be related to the level of fluid upon which the barrel floats.
The signal processor is calibrated with information from known fluid system input flow and then the processor electronically integrates the signals from both the barrel sensor and the arm sensor. The processor, or an auxiliary component such as a computer, can then record and display the velocity and/or volumetric rate of fluid flow of the moving fluid.